title: The barley MATE gene, HvAACT1, increases citrate efflux and Al(3+) tolerance when expressed in wheat and barley.
abstract: OBJECTIVE
  Aluminium is toxic in acid soils because the soluble Al(3+) inhibits root growth. A mechanism of Al(3+) tolerance discovered in many plant species involves the release of organic anions from root apices. The Al(3+)-activated release of citrate from the root apices of Al(3+)-tolerant genotypes of barley is controlled by a MATE gene named HvAACT1 that encodes a citrate transport protein located on the plasma membrane. The aim of this study was to investigate whether expressing HvAACT1 with a constitutive promoter in barley and wheat can increase citrate efflux and Al(3+) tolerance of these important cereal species.
  
  
  METHODS
  HvAACT1 was over-expressed in wheat (Triticum aestivum) and barley (Hordeum vulgare) using the maize ubiquitin promoter. Root apices of transgenic and control lines were analysed for HvAACT1 expression and organic acid efflux. The Al(3+) tolerance of transgenic and control lines was assessed in both hydroponic solution and acid soil.
  
  
  CONCLUSIONS
  Increased HvAACT1 expression in both cereal species was associated with increased citrate efflux from root apices and enhanced Al(3+) tolerance, thus demonstrating that biotechnology can complement traditional breeding practices to increase the Al(3+) tolerance of important crop plants.
authors.affiliation: Tasmanian Institute of Agriculture, University of Tasmania, PO Box 46, Kings Meadows, TAS 7249, Australia.
authors.forename: Gaofeng
authors.initials: G
authors.lastname: Zhou
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Delhaize
authors.forename: Meixue
authors.initials: M
authors.lastname: Zhou
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ryan
mesh_terms: D000535:Aluminum / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019343:Citric Acid / Q000378:metabolism*; D001467:Hordeum / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000378:metabolism; D014908:Triticum / Q000235:genetics*
chemical_list: D002352:Carrier Proteins; D010940:Plant Proteins; D019343:Citric Acid; D000535:Aluminum
keywords: Acid soil; Hordeum vulgare; Triticum aestivum; aluminium; barley; resistance; tolerance; transgenic; wheat